WASP-8b

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WASP-8b
Exoplanet Comparison WASP-8 b.png
Size comparison of WASP-8b with Jupiter.
Discovery [1]
Discovered by Cameron et al. (SuperWASP)
Discovery dateApril 1, 2008
Transit
Orbital characteristics [2]
0.0817±0.0006  AU [3]
Eccentricity 0.3057±0.0046
8.158715±0.000016  d
Inclination 88.51°±0.09° [3]
274.21°±0.33°
Semi-amplitude 221.65±1.39  m/s
Star WASP-8
Physical characteristics [3]
1.165±0.032  RJ
Mass 2.216±0.035  MJ
Mean density
1.7370±0.1325  g/cm3
42.5±2.3  m/s2 (4.34 g)
Temperature 1552±85  K (1,279 °C; 2,334 °F) [4]

    WASP-8b is an exoplanet orbiting the star WASP-8A in the constellation of Sculptor. The star is similar to the Sun and forms a binary star with a red dwarf star (WASP-8B) of half the Sun's mass that orbits WASP-8A 4.5 arcseconds away. The system is 294 light-years (90 parsecs ) away and is therefore located closer to Earth than many other star systems that are known to feature planets similar to WASP-8b. The planet and its parent star were discovered in the SuperWASP batch -6b to -15b. On 1 April 2008, Dr. Don Pollacco of Queen's University Belfast announced them at the RAS National Astronomy Meeting (NAM 2008). [5]

    Contents

    Orbit

    The planet orbits WASP-8A at an average distance of just 0.08  AU (12,000,000  km ) and a year passes in slightly more than 8.1 days on WASP-8b, which is somewhat farther from its parent star than other hot Jupiter planets. However, WASP-8b's orbit also has a relatively high eccentricity of 0.3, which, at periastron, brings it as close to its star as said similar planets are.

    One thing that stands out extremely about WASP-8b is its orbit-spin angle to its star of 123°+3.4°
    −4.4°    : This implies that the planet actually orbits retrograde to the spin of the parent star. [6] [1] [7]

    Physical characteristics

    WASP-8b belongs to a class of extrasolar planets known as hot Jupiters and has a mass about 2.2 times and a radius slightly bigger than that of the planet Jupiter. Its density is about 1.737 g/cm3; this implies that, unlike similar close-orbiting gas giants, the planet is actually denser than Jupiter (which has a density of 1.326 g/cm3). [8]

    Owing to its close distance to its star, WASP-8b is extremely hot: Its measured dayside temperature is 1,552 K (1,279 °C), this is even hotter than its equilibrium temperature of 947 K (674 °C). [8] [4]

    See also

    References

    1. 1 2 Didier Queloz; et al. (2010). "WASP-8b: a retrograde transiting planet in a multiple system". Astronomy and Astrophysics. 517: L1. arXiv: 1006.5089 . Bibcode:2010A&A...517L...1Q. doi:10.1051/0004-6361/201014768. S2CID   35774603.
    2. ↑ Bonomo, A. S.; Desidera, S.; et al. (June 2017). "The GAPS Programme with HARPS-N at TNG. XIV. Investigating giant planet migration history via improved eccentricity and mass determination for 231 transiting planets". Astronomy & Astrophysics . 602: A107. arXiv: 1704.00373 . Bibcode:2017A&A...602A.107B. doi:10.1051/0004-6361/201629882.
    3. 1 2 3 Southworth, J.; Bohn, A. J.; Kenworthy, M. A.; Ginski, C.; Mancini, L. (2020), "A multiplicity study of transiting exoplanet host stars", Astronomy & Astrophysics, 635: A74, arXiv: 2001.08225 , Bibcode:2020A&A...635A..74S, doi:10.1051/0004-6361/201937334, S2CID   210860775
    4. 1 2 Cubillos, Patricio; Harrington, Joseph; et al. (May 2013). "WASP-8b: Characterization of a Cool and Eccentric Exoplanet with Spitzer". The Astrophysical Journal . 768 (1): 42. arXiv: 1303.5468 . Bibcode:2013ApJ...768...42C. doi:10.1088/0004-637X/768/1/42.
    5. ↑ "SuperWASP scoops ten exoplanets in six months". Astronomy Now . 2008-04-01.
    6. ↑ European Southern Observatory. "Artist's impression of an exoplanet WASP 8b in a retrograde orbit".
    7. ↑ Albrecht, Simon; Winn, Joshua N.; Johnson, John A.; Howard, Andrew W.; Marcy, Geoffrey W.; Butler, R. Paul; Arriagada, Pamela; Crane, Jeffrey D.; Shectman, Stephen A.; Thompson, Ian B.; Hirano, Teruyuki; Bakos, Gaspar; Hartman, Joel D. (2012), "Obliquities of Hot Jupiter Host Stars: Evidence for Tidal Interactions and Primordial Misalignments", The Astrophysical Journal, 757 (1): 18, arXiv: 1206.6105 , Bibcode:2012ApJ...757...18A, doi:10.1088/0004-637X/757/1/18, S2CID   17174530
    8. 1 2 Bohn, A. J.; Southworth, J.; Ginski, C.; Kenworthy, M. A.; Maxted, P. F. L.; Evans, D. F. (2020), "A multiplicity study of transiting exoplanet host stars", Astronomy & Astrophysics, 635: A73, arXiv: 2001.08224 , Bibcode:2020A&A...635A..73B, doi:10.1051/0004-6361/201937127, S2CID   210861118

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